[WIP] Bump supported browsers for v5 (twbs#28317)

* Bump supported browsers for v5

- Chrome history: https://en.wikipedia.org/wiki/Google_Chrome_version_history
- Firefox latest ESR (v60): https://www.mozilla.org/en-US/firefox/organizations/
- Edge history: https://en.wikipedia.org/wiki/Microsoft_Edge#Release_history
- Desktop Safari history: https://en.wikipedia.org/wiki/Safari_version_history
- Opera history: https://help.opera.com/en/opera-version-history/

* Update .browserslistrc

* Roll back Chrome several versions for now

Still WIP, but wanting to get this merged, so finding a slightly wider baseline

.browserslistrc

@@ -3,11 +3,11 @@
 >= 1%
 last 1 major version
 not dead
-Chrome >= 45
-Firefox >= 38
-Edge >= 12
+Chrome >= 60
+Firefox >= 60
+Edge >= 15.15063
 Explorer 11
-iOS >= 9
-Safari >= 9
-Android >= 4.4
-Opera >= 30
+iOS >= 10
+Safari >= 10
+Android >= 6
+not ExplorerMobile <= 11